Does Reheating Leftovers Kill Vitamins?

From the WebMD Archives

By Shannon Bevins

The Rumor: Dinner is less nutritious the second time around

Leftovers are a sanity saver for many. Making large meals with the intent of having leftovers is a key time-management tool for parents juggling hectic schedules. That said, there are food purists out there who seem to think that reheating food -- particularly in a microwave -- is akin to eating a plate of hazardous seconds shipped straight from Fukushima. But will nuking that leftover meatloaf kill its vitamin content? Is it healthier to reheat food in the oven or on the stove?

The Verdict: When reheating leftovers, microwaving is best

While the mineral content of food isn't affected by microwaving, the vitamin content does take a bit of a hit when food is reheated. (Vitamin C and the B vitamins are especially affected.) Still, the microwave isn’t the villain that it's often made out to be. To understand why, we need to look at how it works. Basically, the microwave is uber talented at exciting water molecules. In fact, the energy manufactured by a microwave zeroes in on the water molecules in food. The water molecules essentially ignite a raging party amongst themselves, going from warm to hot in seconds.

Some nutrients -- especially Vitamin C -- break down during any heating process, so reheating via a speedy microwave is actually ideal. (Ovens and toasters may zap a greater percentage of nutrients than a microwave due to length of cooking time.) "Vitamin C is more heat-sensitive than many other water-soluble vitamins and antioxidants, so you do run the risk of losing some C when you reheat your leftovers," says upwave reviewer Caroline Kaufman, M.S., RDN. "However, microwaving does a great job of preserving nutrients that would otherwise leach out into cooking water or break down when food is overcooked."